The present invention relates to defoaming devices for foamable products. Specifically, the present invention relates to a defoaming device utilized on a packaging machine to decrease the foam level in a container prior to sealing of the container.
In the packaging industry, productivity is synonymous with the ability to produce a greater number of cartons per hour than previous machines. In the field of form, fill and seal packaging machine, the ability to produce higher capacity machines is accomplished by analyzing, and as necessary, modifying each action performed on the machine. Through analyzing each action performed on the machine, the dwell time may be lessened while the indexed movement is increased in order to achieve higher capacity on the packaging machine. The dwell time is defined as the time period that each preformed container is stationary on the machine while an action is performed on the container. The indexed movement is defined as the time period that each pre-formed container is conveyed along the packaging machine from one station to the next.
For example, on a linear form, fill and seal packaging machine such as a TETRA REX(copyright) packaging machine available from Tetra Pak, Incorporated of Chicago, Ill., once a pre-formed container is filled with a product, conveyance of the container must be controlled to prevent sloshing of the product onto the sealing area of the container. However, it is desired to increase the conveyance speed of the product-filled container. To that end, the motion profiles of the conveyance of containers is controlled as set forth in U.S. Patent No. (co-pending U.S. patent application Ser. No. 08/848,888) entitled Servo-Controlled Conveyor System For Carrying Liquid Filled Containers, assigned to the assignee of the present invention.
Another possibility for increasing capacity would be to reduce the number of indexed dwell positions on the conveyor line. One possible dwell position that may be eliminated is the extra dwell position between the filling station and top sealing station. This station allows for the product foam in a recently filled container to settle prior to top sealing, which prevents wetting of the sealing area of the container with product foam. Other packaging machines such as rotary filling machines and vertical form, fill and seal machines have exhibited similar problems with foamable products.
One defoaming technique is set forth in U.S. Pat. No. 4,295,502, entitled xe2x80x9cMethod And Apparatus For The Elimination Of Foam Above The Level Of A Liquid, And Particularly Above A Packaged Liquid Such As Milk.xe2x80x9d This technique discloses the use of ultrasonic waves to decrease the product foam in a container through disruption of the foam bubbles. The technique requires ultrasonic equipment positioned above the conveyor line. However, the ultrasonic device will increase the noise level on the packaging machine, and if other ultrasonic devices are employed on the machine, such as ultrasonic fitment applicators, then already high decibel levels may be doubled, coming close to intolerable decibel levels. Safeguards and other additions may be added to the machine to reduce noise, however, this further increases the cost of the packaging machine. Moreover, the use of ultrasonics for defoaming purposes has proven ineffective.
An alternative defoaming device is needed in the packaging industry to increase the packaging capacity of machines. Such a device desirably reduces foaming of the newly filled package, with minimal if any impact on the operating speeds of the overall packaging machine operation. Most desirably, such a device fits within the known physical parameters and sizing of known packaging machines.
The present invention provides an alternative to ultrasonic defoaming which effectively defoams a container filled with a foamable product. The present invention accomplishes this by providing a defoaming device that creates a shock wave to destroy or collapse the bubbles of a foamable product inside a container after filling.
One aspect of the invention is a defoaming device having a body with a reflective recessed cavity. Inside the cavity are two electrical terminals that, when a voltage is applied to one terminal, an arc is created between the terminals to complete the circuit. The discharge or arc superheats the air inside of the recessed cavity to create a shock wave. The shock wave is directed toward the container to destroy the bubbles of the foam.
Another aspect of the invention is a packaging machine having such a defoaming device positioned between a filling station and a top sealing station. Yet another aspect of the invention is a method for defoaming a carton filled with a foamable product. It is a primary object of the present invention to provide a method and apparatus to defoam pre-formed containers filled with a product on a packaging machine.